1. Field of Invention
The present invention relates generally to the field of wireless communication and data networks. More particularly, in one exemplary aspect, the present invention is directed to compensating for or mitigating the effects of electromagnetic signal interference in devices implementing two or more wireless air interfaces or protocols.
2. Description of Related Technology
The effective implementation of convergence products has led to a revolution in the way consumers view computerized devices. These next generation computerized devices focus on offering consumers a substantially unified solution for a variety of services to which consumers have become accustomed. One example of such a converged solution is the exemplary “M82” laptop computer or iPhone™ each manufactured by the Assignee hereof, which support a variety of wireless protocols and other functions. For instance, the iPhone™ has the capability of, among other things, sending and receiving emails over a WLAN network, making and receiving calls using a GSM cellular network, and operating wireless peripheral equipment (such as wireless headsets) using the Bluetooth protocol.
As technologies converge, implementation requirements and constraints, including cost, size, and antenna isolation in these hardware systems inevitably will introduce difficulties which can potentially result in a poor user experience with the device. For example, both Bluetooth and WLAN (802.11b/g/n) share the same ISM band in the 2.4-2.8 GHz frequency range. Due to the close physical proximity of these wireless interfaces (including their antenna) in these converged or unified devices, the Bluetooth and WLAN technologies can interfere with each other when operating simultaneously, and can cause problems such as for example Bluetooth audio stutter and drop-outs, slow WLAN transfer speeds, poor Bluetooth mouse tracking, etc.
Several solutions have been contemplated in the prior art to address the co-existence problems of co-located or proximate wireless technologies. For example, United States Patent Publication No. 20070099567 to Chen; et al. published May 3, 2007 and entitled “Methods and apparatus for providing a platform coexistence system of multiple wireless communication devices” discloses various embodiments of methods and apparatus for providing a platform coexistence system of multiple wireless communication devices.
United States Patent Publication No. 20070080781 to Ginzburg; et al. published Apr. 12, 2007 and entitled “Device, system and method of coordination among wireless transceivers” discloses devices, systems and methods of coordination among wireless transceivers. For example, an apparatus in accordance with an embodiment of the invention includes first and second wireless transceivers, wherein the first wireless transceiver is to enter a non-transmission mode for a pre-defined time period in response to an indication from the second wireless transceiver, and wherein one of the first and second wireless transceivers is to operate in a synchronous network and the other of the first and second wireless transceivers is to operate in a non-synchronous network.
United States Patent Publication No. 20070060055 to Desai; et al. published Mar. 15, 2007 and entitled “Method and system for antenna and radio front-end topologies for a system-on-a-chip (SOC) device that combines Bluetooth and IEEE 802.11 b/g WLAN technologies” discloses a method and system for antenna and radio front-end topologies for a system-on-a-chip (SOC) device that combines Bluetooth and IEEE 802.11 b/g WLAN technologies. A single chip radio device that supports WLAN and Bluetooth technologies receives a WLAN signal in a WLAN processing circuitry of the radio front-end and in a Bluetooth processing circuitry of the radio front-end. Signals generated by the WLAN processing circuitry and the Bluetooth processing circuitry from the received WLAN signal may be combined in a diversity combiner that utilizes selection diversity gain combining or maximal ratio combining (MRC). When a generated signal is below a threshold value, the signal may be dropped from the combining operation. A single antenna usage model may be utilized with the single chip radio device front-end topology to support WLAN and Bluetooth communications.
United States Patent Publication No. 20060274704 to Desai; et al. published Dec. 7, 2006 and entitled “Method and apparatus for collaborative coexistence between Bluetooth and IEEE 802.11g with both technologies integrated onto a system-on-a-chip (SOC) device” discloses a method and system for collaborative coexistence between Bluetooth and IEEE 802.11g with both technologies integrated onto an SOC device. In a single integrated circuit (IC) that handles Bluetooth and WLAN technologies, a WLAN priority level may be selected for WLAN transmissions and a Bluetooth priority level may be selected for Bluetooth transmissions. The WLAN and Bluetooth priority levels may be selected from a plurality of priority levels. A packet transfer scheduler (PTS) may schedule the transmission of WLAN and Bluetooth signals in accordance with the selected priority levels. In some instances, the PTS may promote or demote the priority levels for WLAN and/or Bluetooth transmissions based on traffic needs.
United States Patent Publication No. 20060133259 to Lin; et al. published Jun. 22, 2006 and entitled “Interference rejection in wireless receivers” discloses a wireless system which mitigates the effects of interference through updating noise variance estimates. Noise variance estimates may be updated after the reception of a preamble in an OFDM receiver.
United States Patent Publication No. 20060084383 to Ibrahim; et al. published Apr. 20, 2006 entitled “Method and system for collocated IEEE 802.11 B/G WLAN, and BT with FM in coexistent operation” discloses a method and system for collocated IEEE 802.11 b/g WLAN, and Bluetooth (BT) with FM in coexistent operation are provided. A single chip comprising an integrated BT radio and an integrated FM radio in a coexistence station may generate a priority signal to disable WLAN transmissions in a WLAN radio when a BT HV3 frame is available for transmission. When the priority signal is asserted, an exponentially growing retransmission backoff mechanism in the WLAN radio may be disabled. Moreover, when the BT radio and the WLAN radio are enabled for coexistence operation, a WLAN fragmentation threshold in the WLAN radio may be modified based on a WLAN modulation rate and the BT HV3 frame duration. An on-chip processor that time multiplexes FM and Bluetooth data processing may be utilized to control the BT radio operation and the FM radio operation in the single chip.
United States Patent Publication No. 20060030266 to Desai; et al. published Feb. 9, 2006 and entitled “Method and system for achieving enhanced quality and higher throughput for collocated IEEE 802.11B/G and Bluetooth devices in coexistent operation” discloses a method and system for achieving enhanced quality and higher throughput for collocated IEEE 802.11b/g and Bluetooth (BT) devices in coexistent operation are provided. A priority signal may be generated by a BT radio in a coexistence station to disable WLAN transmissions in a WLAN radio when a BT HV3 frame is available for transmission. When the priority signal is asserted, an exponentially growing retransmission backoff mechanism in the WLAN radio may be disabled. Moreover, when the BT radio and the WLAN radio are enabled for coexistence operation, a WLAN fragmentation threshold in the WLAN radio may be modified based on a WLAN modulation rate and the BT HV3 frame duration.
United States Patent Publication No. 20060030265 to Desai, et al. published Feb. 9, 2006 entitled “Method and system for sharing a single antenna on platforms with collocated Bluetooth and IEEE 802.11 b/g devices” discloses a method and system for sharing a single antenna on platforms with collocated Bluetooth and IEEE 802.11 b/g devices. A single antenna may be utilized for communication of Bluetooth HV3 frame traffic and wireless local area network (WLAN) communication based on a time multiplexing approach. At least one antenna switch may be utilized to configure an antenna system to enable Bluetooth and WLAN coexistence via the single antenna. Configuration signals may be generated by a Bluetooth radio device and/or by a WLAN radio device to configure the antenna system. A default configuration for the antenna system may provide WLAN communication between a station and a WLAN access point until Bluetooth communication becomes a priority.
United States Patent Publication No. 20050215197 to Chen, et al. published Sep. 29, 2005 and entitled “Apparatus and methods for coexistence of collocated wireless local area network and Bluetooth based on dynamic fragmentation of WLAN packets” discloses an 802.11—enabled device may fragment an 802.11 packet into smaller packets and transmit the smaller packets instead of the 802.11 to lessen interference with Bluetooth synchronized connection-oriented communication of a collocated or nearby Bluetooth-enabled device.
Despite the foregoing variety of different approaches, the prior art neither teaches nor suggests an effective technique for compensating for the effects of interference based on an operational criteria (e.g. antenna isolation). Additionally, prior art solutions tend to focus on a “one size fits all” solution that does not take into account the various features and services offered to optimize the user experience.
Accordingly, improved methods and apparatus for compensating for the effects of interference between wireless technologies that at least partly operate in the same frequency bands are needed. Ideally, such improved methods and apparatus could be implemented as either a “closed-loop” (i.e., device communicating with its associated access point or AP for example) or “open-loop” (functionality entirely within the device) manner, thereby increasing the flexibility to compensate for interference according to any number of factors including, but not limited to: (i) antenna isolation, (ii) user priorities, (iii) application priorities, (iv) usage characteristics for the system, and (v) network/AP-related considerations.
Such methods and apparatus would also ultimately provide the user with the best use experience possible, while offering converged services in a unified client device in a space- and power-efficient manner.